@conference{
author = "Parabucki, Ana and Korać, Bato and Otašević, Vesna and Bjelobaba, Ivana and Lavrnja, Irena and Stojiljković, Mirjana and Nedeljković, Nadežda",
year = "2009",
abstract = "Povreda mozga obuhvata primarnu povredu, koja nastaje kao rezultat
neposrednog mehaničkog oštećenja tkiva i sekundarnu povredu koja se javlja tokom
perioda od narednih nekoliko dana. Iako još uvek nisu poznati svi detalji mehanizama
koji dovode do sekundarne povrede, nekoliko metaboličkih promena, uključujući i
povećanje produkcije reaktivnih kiseoničnih vrsta (ROS) dovedeno je u vezu sa
patofiziologijom sekundarne povrede. Budući da su mitohondrije primarno
unutarćelijsko mesto nastanka ROS, pretpostavlja se da mangan superoksid dismutaza
(MnSOD, SOD2) ima presudnu zaštitnu ulogu u antioksidativnim mehanizmima
odbrane i preživljavanju nervnih ćelija nakon povrede. Stoga je u ovom radu praćena
ekspresija MnSOD u modelu unilateralne ablacije korteksa pacova, sa ciljem da se
rasvetli njena uloga u ranim događajima nakon povrede mozga.
Svi eksperimenti izvedeni su na pacovima soja Wistar starim tri meseca.
Životinjama je pod anestezijom Zoletilom, uklonjen senzomotorni korteks na levoj
strani, pažljivim usisavanjem tkiva kroz polipropilenski vrh. Životinje se žrtvovane 0, 4,
24 i 72 časa nakon povrede i tkivo levog (LCtx) i desnog (RCtx) korteksa disecirano je i
iskorišćeno za pripremu tkivnih homogenata. Za svaku eksprimentalnu tačku, korišćena
je grupa lažno operisanih životinja, dok su neoperisane, intaktne životinje primenjene
kao fiziološka kontrola. Intenzitet signala ekspresije iRNK i proteina kod povređenih
životinja izražen je u odnosu na lažno-operisane životinje, dok je intenzitet dobijen kod
intaktnih životinja arbitrarno definisan kao 1.00.
RtPCR analiza demonstrirala je da u LCtx dolazi do rane indukcije iRNK za
MnSOD između 4 i 24 h nakon povrede. Uočeno vremenski-zavisno povećanje iRNK za
MnSOD bilo je najveće 4 sata nakon povrede. Saglasno tome, imunoblot analiza
pokazala je da je ekspresija MnSOD proteina u LCtx značajno povećana tokom prva
četiri sata nakon povrede. Ekspresija iRNK i MnSOD proteina vraća se na fiziološki
nivo 72 sata nakon povrede. S druge strane, ekspresija MnSOD, kako na nivou iRNK,
tako i na nivou proteina, ne menja se u RCtx tokom celog eksperimentalnog perioda.
Rezultati ovog rada ukazuju da povreda mozga dovodi do brzog i značajnog
povećanja ekspresije MnSOD na mestu povrede, najverovatnije kao deo odgovora na
oksidativni stres uzrokovan primarnom povredom. Budući da MnSOD predstavlja prvu
liniju odbrane od superoksid anjon radikala koji nastaju u mitohondrijama, ovi nalazi
mogu doprineti boljem razumevanju uloge MnSOD u procesu oporavka nakon povrede., Brain injury consists of primary injury that is the result of immediate
mechanical damage and secondary injury that evolves over a period of minutes and
days. The precise mechanisms underlying secondary injury are not well understood,
however several metabolic dearangements, including increased generation of reactive
oxygen species (ROS) have been implicated in the pathophysiology following brain
damage. Since mitochondria are the major subcellular site of ROS generation,
manganese superoxid dismutase (MnSOD, SOD2), a potent scavanger of superoxide
radicals could have critical cytoprotective role in the antioxidant defence mechanism and
neuronal survival after brain damage. Thus, in the present study we have evaluated
expression of MnSOD to address its role during early events of brain injury using a
model of unilateral cortical ablation in rat.
Experiments were performed on three-month old Wistar male rats. The
sensomotory cortex was unilaterally removed on the left side by gentle suction
aspiration through polypropilene tip under the Zoletil anesthesia. Animals were
sacrificed 0, 4, 24 and 72 hours after the surgery and left (LCtx) and right (RCtx)
cortical tissues were immediately isolated for tissue homogenate preparations. For each
time point, another group of aged-matched animals was used as sham-operated controls,
whereas non-operated, intact animals were used as a physiological control. Signal
intensities obtained for MnSOD mRNA and protein expression in injured animals were
expressed relative to that obtained for sham-operated animals at each time point after the
surgery, whereas signal intensity obtained for intact control was arbitrarily defined as
1.00.
RtPCR analysis showed a rapid induction of MnSOD mRNA in LCtx between 4
and 24 h after the injury. Observed time-dependent increase in MnSOD mRNA was
maximal 4 hours after the injury compared to the level induced by sham operation alone.
Accordingly, immunoblot analysis demonstrated increased expression of MnSOD
protein in LCtx up to 4 h after the injury. 72 hours after the injury MnSOD mRNA and
protein expression return to the level of the intact control. On the other hand, MnSOD
mRNA and protein expression remained unaffected in the RCtx at all time points after
the surgery.
In conclusion, the result of this study demonstrate that brain injury induce rapid
and marked increase in MnSOD expression at the site of injury, most likely as a
protective response after oxidative stress initiated by primary brain damage. Since
MnSOD provides the first line of defense against superoxide generated in mitochondria,
these findings may contribute to a better understanding of role MnSOD in the recovery
process following brain injury.",
publisher = "Belgrade : Serbian Society for Mitochondrial and Free-Radical Physiology",
journal = "Knjiga sažetaka: Naučni simpozijum: Mitohondrije i slobodni radikali - nov izazov; 2009 Sep 21; Belgrade, Serbia",
title = "Rano povećanje ekspresije mangan superoksid dismutaze nakon eksperimentalne povrede mozga pacova",
pages = "58-59",
url = "https://hdl.handle.net/21.15107/rcub_ibiss_6064"
}
